The Colorado Craniosynostosis Registry was established on April 15, 1986 to investigate the occureence of craniosynostosis (CS) in Colorado. Statewide concern arose after a 1978 cluster report and again after a 1983 study that found a higher birth prevalence of CS in Colorado than in Atlanta. During the first six months of operation, 218 eligible children were reported to the registry, corresponding to an estimated birth prevalence of almost one percent statewide, with county-specific birth prevalences as high as 18 percent. This population-based case-control study will seek to identify risk factors for CS occurrence in Colorado. Children with CS will be identified prospectively through the statewide registry. Control children will be identified through random sampling of Colorado birth certificates. Mothers of normal and affected children will be interviewed by telephone regarding their child's exposure to potential risk factors for CS such as obstetric, occupational, and environmental factors. Hospital records of the mother and child will be reviewed for record of exposure to potential risk factors such as abnormal lie and birth trauma. The exposure histories of control children and children with CS will be compared using stratified analysis and logistic regression. Some analyses will estimate the association between CS and previously hypothesized risk factors, like fetal head constraint, while others will seek evidence of association with newly hypothesized risk factors for CS such as high attitude. Familial aggregation of CS will be examined in the same manner, with furhter genetic epidemiologic analysis as indicated. The analyses will be repeated among controls and children with CS of unknown etiology. The occurrence of CS is largely unexplained. Increased understanding of factors associated with this common defect may provide clues for future epidemiologic and laboratory research, and may provide a first step toward primary prevention of the defect.